[Feature Request] Add Variants of Storage API that accept passed in db.Tx

[Zhennan-Xu]

When writing complex custom rpcs, it is often desired to have control over the db transaction lifecycle. The storage APIs however start their own transaction; to avoid isolation issues, it would be ideal if the storage APIs could have additional variants that accept a pre-existing transaction.

relevant post:
https://forum.heroiclabs.com/t/feature-request-add-variants-of-storage-api-that-accept-passed-in-db-tx/426

[linear]

NK-1682 [Feature Request] Add Variants of Storage API that accept passed in db.Tx